This invention pertains to a fitting for a hose article and more particularly to a fitting for the end portion of a hose, which is solidly embedded in the wall of the hose.
In hoses, especially large industrial hoses, some type of fitting has to be installed on the end of the hose in order to connect it to either another hose or to a pipe, a valve, or some other piece of plumbing. One way of achieving contact and connection with a hose end is to use some sort of a flange arrangement. A flange is usually some sort of rim that projects outwards from a pipe or tube or hose at a right angle, giving the appearance of a collar. Often, holes are bored into the flange, which are lined up with holes that have been bored into another flange on the fixture that the hose is to be connected to, and then bolts are inserted through the holes that have been lined up in this way. When the bolts are tightened down, a seal is formed between the end of a hose and whatever other fixture the hose is thus attached to.
It has been a common practice in manufacturing larger industrial hoses to build up the end-most portion of the hose to be thicker than the rest of the hose, and therefore form a shoulder. This shoulder is useful in acting as a stop against which the flange can get a good grip on the hose. The problem with this arrangement is that after the flange has been mounted on the hose and is pushed up tight against the shoulder and is bolted onto the neighboring flange, that whenever the hose flexes, a great deal of stress will tend to concentrate on the area just behind the flange on the hose. This results in premature cracking and failure of the hose in this critical area just behind the shoulder and the flange. Therefore, ways were sought-after to move this area of stress farther away from the end area of the hose.
The shoulder at the end of the hose is usually built up by attaching a circular ring onto one of the inner layers of the hose, and then applying more layers of rubber over the inner layers of rubber and the ring as well, so as to build up the shoulder. It was realized that if the ring were solidly mounted onto a cylinder to fit over the inner layers of rubber, and then if, outer layers of rubber were applied over the ring and cylinder combination, then the area of stress would be moved away from the very end of the hose and the stress would be distributed along the length of the cylinder. This tended to reduce premature failure of the hose by cracking at the end portion behind the flange.
This solution had its own problems, however. Usually, the cylinder (or "nipple" as it is more properly referred to) would be made of metal. It is very difficult to obtain a good adhesive bond between rubber and metal, so that a new mode of failure emerged: the rubber would blister away, and separate from, the metal of the nipple. Therefore, a need arose for a nipple that could be seated within a hose having a ring structure on it to provide the basis for a shoulder to mount a flange on, and which could be so firmly anchored into the walls of the hose as to minimize separation of the bond between the nipple and the walls of the hose, and yet be economical to manufacture and use. The present invention is a solution to these longfelt needs.